Elevating mechanism for machine tool knees



Jam 4,1944 F. W. CURTIS ELEVATNG MECHANSM FOR MACHINE TOOL KN EES Original.` Filed March 8, 1940 2 Sheets-Sheet 1 llllll Iv Jan. 4, 1944. F. W CURTlS 2,338,624

ELEVATING MECHANISM FOR MACHINE TOOL KNEES @ya w Original Filed March 8, 1940 2 Sheets-Sheet 2 INVENTOR IRA/wf WUfU/s BY A 7 Z ATTO" NEYS Patented Jan. 4, 1944 LEVATNG NIECHANISM FOR MACHINE TOOL KNEES Frank W. Curtis, Springield, Mass., assignerL to Van Norman Company, a corporation of Massachusetts Original application March 8, 1340, Serial No.

322,973, now Patent No. 2,301,525, dated November lil, 1942. Divided andths application November 27, 194i), Serial No. 367,326

1 Claim.

This invention relates to improvements in ele'- vating mechanism for the knees of machine tools, and is a division of my application Serial No. 322,973, led March 8, 1940, now Patent No. 2,301,525, granted November l0, 1942.

One object of the invention is to improve the knee structure solas to give improved stability and guidance to the elevating mechanism and so that the elevating mechanism itself will contribute to the stability of the knee. A further object is to improve the drive and stability of operation of the knee to the end that smooth operation and freedom from chatter will be present even when the elevating mechanism is driven at a rapid traverse rate. A further object is to provide a construction of knee elevating mechanism in which the telescopic parts extending between the vertically movable knee and base will have a maximum protection against dirt and metal chips. A further object is to provide a construction which will prevent leakage of oil from the interior of the knee when, as is preferable, the knee acts as an oil reservoir for the gearing contained in it. Additional objects will appear from the following description and claim.

Referring to the drawings,

Fig. l is a side elevation, partly broken away, of a machine tool knee embodying the present invention;

Fig. 2 is a sectional plan through the knee structure;

Fig. 3 is a detail of the knee elevating screw;

Fig. 4 is an enlarged detail of a portion of Fig. l;V and Fig. 5 is a diagrammatic View ci the gearing for operating the knee elevating mechanism at either feed or rapid traverse rate.

The machine is shown as mounted on a base A, a column B arising from the base and having ways upon which the knee C slides vertically. Additional parts, such as a saddle and la table, are generally used in connection with the knee, and have been described in the parent application referred to. Parts other than those conce1-ned in giving the knee its vertical movement have been omitted from the present disclosure.

The power feed for the knee is derived from a vertical shaft 2) mounted in the base A and extending vertically into telescoping relation with the knee. This shaft may be driven from a suitable motor in a way not necessary to show here. The shaft 2l) is splined as is shown in Figs. 2 and 4. and passes through the downwardly projecting shank 2l of a bevel gear 22 held in the knee structure by anti-friction bearings 23, In order to keep oil from leaking down the'splines on this shaft a sleeve 24 is fitted into the bevel gear 22 and extends upwardly nearly to the top of the knee, being provided with ya cap 25. InFig, l the knee is shown in its lowermost position, and as the knee rises, the shank 2| and the sleeve v 2d will 'slide upwardly on the splined shaft.

Meshing with the gearing 22 is a second bevel gear 2S, the shank 2l of which is mounted in anti-friction bearings carried by theknee structure. The shank 2l carries one member 2S of a rapid traverse friction clutch, here shown being oi a standard multiple plate type, The driven clutch member Sil is carried by a sleeve Rl reciprocable upon a common drive shaft which is splined at its end adjacent the sleeve so that while the sleeve may reciprocate upon the shaft it is always coupled in driving relation to it. As will be seen from Fig. 'l the shaft :i2 `has a bearing portion 33 within the shank 2 of the gear 245.

The knee elevating mechanism is driven from the common drive shaft 32; and this shaft, as well as being driven directly from the gear 26 through the rapid traverse clutch, may also be driven through the gearing now to be described at any `of eighteen feed rates. For this purpose a gear 35 (see Fig. 2) is secured to the face of the bevel gear 26 and meshes with a gear St rotatably mounted in the knee structure. Fixed to the gear 36 is a pinion 37 meshing with a gear 33. Positively coupled to this latter gear is a second pinion 39 meshing with a gear 40 coaxial with the gear 36. A splined shaft il! (Fig. 5) passes freely through the gear ll and has coupled to it a clutch member 42 shiftable alternatively into engagement with cooperating complementary clutch members formed on gear 38 and gear titl. In this way the splined shaft 4l may be driven either directly from the constantly rotating gear 35 or through the gear train 31, Bt, 3Q, fill which acts similarly to back gears to produce a lower rate of rotation of the driven The splined shaft lll carries Ia gear 43 meshing with a larger gear fifi upon a shaft l5 (Figs. 2 and 5) journaled in the knee and provided at its end remote from the gear 4B with a splined portion upon which a cluster gear 48 slides. This gear is composed of three gears 4l', GS, and 52 which mesh respectively with gears 5i?, 5l, and 52 upon a parallel idler shaft 53. A second cluster gear is mounted for reciprocation on a splined sleeve 55 journaled for free rotation about the common drive shaft 32 previously described. This second cluster gear comprises gears 56, 51, land 58 meshing respectively with gears 59, 5|, and 60 on the intermediate shaft 53. By shifting the cluster gear 46 three changes of feed rate may be secured. Each of these can be varied in three Ways by shifting the cluster gear 54, making a total of nine changes of feed rate for sleeve 55, and each of these nine feed rates may be varied from a high rate to a low rate by means of the clutch 42, making a total of eighteen possible feed rates.

The splined sleeve 55, see Figs. 1, 2 and 5, carries a clutch member 6| cooperating with a clutch member 62 on the sleeve 3| previously referred to as being keyed on the drive shaft 32. This drive shaft extends to the front of the knee and has fixed to it a gear 61 which may, as set forth in the parent application, be formed as an overload release. Gear 61 meshes with a wide-faced gear 15. A gear 11 upon a reversing shaft 18 meshes with gear 15, the shaft 18 also having a gear 'i9 iixed to it. The knee drive shaft 80 has gears 8| and 82 mounted to revolve freely about it, the former meshing with the wide-faced gear and the latter with the reversing gear 19. The gears 8| and 82 are provided with clutch teeth and a clutch 8? splined to the shaft 8|) may be moved into contact with either of them to cause the shaft 8G to be rotated in one direction or the other or to be held inoperative by leaving the clutch in its central idle position.

Passing now to the mechanism by which the knee is elevated either by power or manually; the knee drive shaft 80, which is journaled in the removable front plate 66 at 85 and also in the knee structure at 96, carries a bevel gear 9'! meshing with a larger bevel gear 98 on a vertical axis. As is shown in Fig. 3, the gear 98 has a shank 99 mounted in anti-friction bearings Iil carried by the knee, the gear being held to these bearings by a shoulder on one side and by a threaded collar on the other. The shank 99 is held by screws |02 to the enlarged top w3 of the elevat- 5 ing screw |54 which extends downwardly toward the base. The elevating screw passes through a nut |65 held as by threading in the upper end of a tube |06. This tube slides through a bearing |61 in theA bottom of the knee, the bearing being 10 preferably provided with a stu'liing box |08 to prevent entrance of dirt or leakage of oil. The tube is clamped at |09 against rotation in the base A.

For manual operation of the knee elevating mechanism a shaft ||0 .is provided, extending parallel to shaft 8|] through the front plate and bearing a handle As appears in Fig. 1 this shaft has fixed on it a gear ||4 which meshes with a gear ||5 on shaft B0. By turning handle shaft 8S is rotated independently of the driving gears tl and 82 and the knee elevating mechanism adjusted.

claim: A knee structure for milling machines and the g5 like comprising a frame, a hollow knee vertically movable on the frame, a vertical splined shaft journaled for rotation upon the frame and having a free end extending upwardly into the knee, a gear splined to the shaft, distributing gearing within the knee coupled to said gear, and a tubular member having a closed upper end and secured to said gear in position to completely enclose that part of the splined shaft above the gear and within the hollow knee to form an oil seal, said closed upper end being remote from the gear a distance substantially corresponding to the maximum vertical travel of the knee.

FRANK W. CURTIS. 

